As a WordPress developer myself, choosing any other platform for my own blog might be considered a bit off the road. But to be honest, it was an easy decision for me as I don't personally like the WordPress' dashboard, it's still 2010'ish and I believe while going for the all-inclusive CMS, there seems a bit too much options (distractions) in the Dashboard, and with the color scheme it has, it just looks boring.
On the other hand, Ghost has a clean & minimal interface, and for anyone who loves to write, I will recommend it on any day.
Actually, I have been using Ghost & WordPress daily for my work (client blogs), and while WordPress has a lot of options, customizations, plugins, etc. when it comes to writing, Ghost has that aura that will flat you the moment you use it! Don't take my word, try it yourself.
I can't really express my joy using this platform, it's such a thing that you need to experience yourself, I bet you will love it just like me & millions of others do.
Are you already using Ghost? I would love to know your experience as well. Add it as a comment below.